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36#include <linux/module.h>
37
38#include <linux/fs.h>
39#include <linux/errno.h>
40#include <linux/miscdevice.h>
41#include <linux/kernel.h>
42#include <linux/major.h>
43#include <linux/mutex.h>
44#include <linux/proc_fs.h>
45#include <linux/seq_file.h>
46#include <linux/stat.h>
47#include <linux/init.h>
48#include <linux/device.h>
49#include <linux/tty.h>
50#include <linux/kmod.h>
51#include <linux/gfp.h>
52
53
54
55
56static LIST_HEAD(misc_list);
57static DEFINE_MUTEX(misc_mtx);
58
59
60
61
62#define DYNAMIC_MINORS 64
63static DECLARE_BITMAP(misc_minors, DYNAMIC_MINORS);
64
65#ifdef CONFIG_PROC_FS
66static void *misc_seq_start(struct seq_file *seq, loff_t *pos)
67{
68 mutex_lock(&misc_mtx);
69 return seq_list_start(&misc_list, *pos);
70}
71
72static void *misc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
73{
74 return seq_list_next(v, &misc_list, pos);
75}
76
77static void misc_seq_stop(struct seq_file *seq, void *v)
78{
79 mutex_unlock(&misc_mtx);
80}
81
82static int misc_seq_show(struct seq_file *seq, void *v)
83{
84 const struct miscdevice *p = list_entry(v, struct miscdevice, list);
85
86 seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : "");
87 return 0;
88}
89
90
91static const struct seq_operations misc_seq_ops = {
92 .start = misc_seq_start,
93 .next = misc_seq_next,
94 .stop = misc_seq_stop,
95 .show = misc_seq_show,
96};
97
98static int misc_seq_open(struct inode *inode, struct file *file)
99{
100 return seq_open(file, &misc_seq_ops);
101}
102
103static const struct file_operations misc_proc_fops = {
104 .owner = THIS_MODULE,
105 .open = misc_seq_open,
106 .read = seq_read,
107 .llseek = seq_lseek,
108 .release = seq_release,
109};
110#endif
111
112static int misc_open(struct inode * inode, struct file * file)
113{
114 int minor = iminor(inode);
115 struct miscdevice *c;
116 int err = -ENODEV;
117 const struct file_operations *old_fops, *new_fops = NULL;
118
119 mutex_lock(&misc_mtx);
120
121 list_for_each_entry(c, &misc_list, list) {
122 if (c->minor == minor) {
123 new_fops = fops_get(c->fops);
124 break;
125 }
126 }
127
128 if (!new_fops) {
129 mutex_unlock(&misc_mtx);
130 request_module("char-major-%d-%d", MISC_MAJOR, minor);
131 mutex_lock(&misc_mtx);
132
133 list_for_each_entry(c, &misc_list, list) {
134 if (c->minor == minor) {
135 new_fops = fops_get(c->fops);
136 break;
137 }
138 }
139 if (!new_fops)
140 goto fail;
141 }
142
143 err = 0;
144 old_fops = file->f_op;
145 file->f_op = new_fops;
146 if (file->f_op->open) {
147 file->private_data = c;
148 err=file->f_op->open(inode,file);
149 if (err) {
150 fops_put(file->f_op);
151 file->f_op = fops_get(old_fops);
152 }
153 }
154 fops_put(old_fops);
155fail:
156 mutex_unlock(&misc_mtx);
157 return err;
158}
159
160static struct class *misc_class;
161
162static const struct file_operations misc_fops = {
163 .owner = THIS_MODULE,
164 .open = misc_open,
165 .llseek = noop_llseek,
166};
167
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182
183
184int misc_register(struct miscdevice * misc)
185{
186 dev_t dev;
187 int err = 0;
188
189 INIT_LIST_HEAD(&misc->list);
190
191 mutex_lock(&misc_mtx);
192
193 if (misc->minor == MISC_DYNAMIC_MINOR) {
194 int i = find_first_zero_bit(misc_minors, DYNAMIC_MINORS);
195 if (i >= DYNAMIC_MINORS) {
196 mutex_unlock(&misc_mtx);
197 return -EBUSY;
198 }
199 misc->minor = DYNAMIC_MINORS - i - 1;
200 set_bit(i, misc_minors);
201 } else {
202 struct miscdevice *c;
203
204 list_for_each_entry(c, &misc_list, list) {
205 if (c->minor == misc->minor) {
206 mutex_unlock(&misc_mtx);
207 return -EBUSY;
208 }
209 }
210 }
211
212 dev = MKDEV(MISC_MAJOR, misc->minor);
213
214 misc->this_device = device_create(misc_class, misc->parent, dev,
215 misc, "%s", misc->name);
216 if (IS_ERR(misc->this_device)) {
217 int i = DYNAMIC_MINORS - misc->minor - 1;
218 if (i < DYNAMIC_MINORS && i >= 0)
219 clear_bit(i, misc_minors);
220 err = PTR_ERR(misc->this_device);
221 goto out;
222 }
223
224
225
226
227
228 list_add(&misc->list, &misc_list);
229 out:
230 mutex_unlock(&misc_mtx);
231 return err;
232}
233
234
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240
241
242
243
244int misc_deregister(struct miscdevice *misc)
245{
246 int i = DYNAMIC_MINORS - misc->minor - 1;
247
248 if (WARN_ON(list_empty(&misc->list)))
249 return -EINVAL;
250
251 mutex_lock(&misc_mtx);
252 list_del(&misc->list);
253 device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
254 if (i < DYNAMIC_MINORS && i >= 0)
255 clear_bit(i, misc_minors);
256 mutex_unlock(&misc_mtx);
257 return 0;
258}
259
260EXPORT_SYMBOL(misc_register);
261EXPORT_SYMBOL(misc_deregister);
262
263static char *misc_devnode(struct device *dev, umode_t *mode)
264{
265 struct miscdevice *c = dev_get_drvdata(dev);
266
267 if (mode && c->mode)
268 *mode = c->mode;
269 if (c->nodename)
270 return kstrdup(c->nodename, GFP_KERNEL);
271 return NULL;
272}
273
274static int __init misc_init(void)
275{
276 int err;
277
278#ifdef CONFIG_PROC_FS
279 proc_create("misc", 0, NULL, &misc_proc_fops);
280#endif
281 misc_class = class_create(THIS_MODULE, "misc");
282 err = PTR_ERR(misc_class);
283 if (IS_ERR(misc_class))
284 goto fail_remove;
285
286 err = -EIO;
287 if (register_chrdev(MISC_MAJOR,"misc",&misc_fops))
288 goto fail_printk;
289 misc_class->devnode = misc_devnode;
290 return 0;
291
292fail_printk:
293 printk("unable to get major %d for misc devices\n", MISC_MAJOR);
294 class_destroy(misc_class);
295fail_remove:
296 remove_proc_entry("misc", NULL);
297 return err;
298}
299subsys_initcall(misc_init);
300